P2189 is the bank 2 version of P2187: on engines with a front oxygen sensor per bank, the long-term trim of bank 2 has to add more fuel than allowed at idle and low load. GM's 2005 2.8 and 3.6 V6 set it when the additive correction exceeds 7 %, the 2008 3.6 LLT above 6.1 % at 520 to 1120 rpm, airflow of 1.7 to 7.8 g/s, engine load of 11 to 45 % and coolant above 60 °C, and GM's 2024 tables above about 5.5 % over two trips. Because both banks share the throttle, crankcase ventilation and brake booster vacuum, a leak there normally lifts the idle trim on both banks, setting P2187 and P2189 together. A code on bank 2 alone points to something only that bank sees: an intake manifold gasket or runner leak on that side, an injector on that bank, or the bank 2 front sensor or its wiring. Comparing both banks' trims at idle and at 2500 rpm narrows it down.
Medium severity. Can I keep driving?You can drive in moderation for a short time. A very lean or very rich mixture can damage the engine or the catalytic converter.
Bank 2 is the side without cylinder 1, so it only exists on V or boxer engines.
Symptoms
- Malfunction indicator lamp on
- Rough or hunting idle
Most likely causes
- Intake gasket or runner leak on the bank 2 side
- Shared vacuum leak, usually with P2187 present too
- Bank 2 front sensor, its wiring or an injector on that bank
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P2189 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 1: Air and fuel
- 89: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2189?
You can drive in moderation for a short time. A very lean or very rich mixture can damage the engine or the catalytic converter.
What causes code P2189?
The most common causes are: intake gasket or runner leak on the bank 2 side; shared vacuum leak, usually with P2187 present too; bank 2 front sensor, its wiring or an injector on that bank.
Related codes
- P2187System Too Lean at Idle (Bank 1)
- P2190System Too Rich at Idle (Bank 2)
- P0174System Too Lean Bank 2
- P2179System Too Lean Off Idle (Bank 2)
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.